Only place I know of is from Ashwin athttp://www.batish.com. Sells 'em for $1.25 apiece. I would recommend you go with the non-coated as soon as you can. Plastic coated mizrabs are loose and tend to move around on your finger when you play.

Hey Neal,Most of the ones I've seen are very small and don't fit. Also, it's well known that your tone will be affected when using the plastic coated mizrabs......If you practice everyday, within a month there won't be any pain on your finger from a regular mizrab and you'll develop callouses........

Hey Neal, one thing I did that helped...Before I even got my Mangla, I had Peter send me a few mizrabs. I wore my misrab during the day, anytime I could, driving to work, etc. You can wear it for short periods of time until you build the callouses. When you need your index finger to accomplish a task, you just wear the mizrab on your pinky, like a ring. - K.K.